//Given a string s, sort it in decreasing order based on the frequency of charac
//ters, and return the sorted string. 
//
// 
// Example 1: 
//
// 
//Input: s = "tree"
//Output: "eert"
//Explanation: 'e' appears twice while 'r' and 't' both appear once.
//So 'e' must appear before both 'r' and 't'. Therefore "eetr" is also a valid a
//nswer.
// 
//
// Example 2: 
//
// 
//Input: s = "cccaaa"
//Output: "aaaccc"
//Explanation: Both 'c' and 'a' appear three times, so "aaaccc" is also a valid 
//answer.
//Note that "cacaca" is incorrect, as the same characters must be together.
// 
//
// Example 3: 
//
// 
//Input: s = "Aabb"
//Output: "bbAa"
//Explanation: "bbaA" is also a valid answer, but "Aabb" is incorrect.
//Note that 'A' and 'a' are treated as two different characters.
// 
//
// 
// Constraints: 
//
// 
// 1 <= s.length <= 5 * 105 
// s consists of English letters and digits. 
// 
// Related Topics 堆 哈希表 
// 👍 243 👎 0


package leetcode.editor.cn;

//Java：Sort Characters By Frequency
 class P451SortCharactersByFrequency {
    public static void main(String[] args) {
        Solution solution = new P451SortCharactersByFrequency().new Solution();
        // TO TEST
    }

    //leetcode submit region begin(Prohibit modification and deletion)
    class Solution {
        public String frequencySort(String s) {
            return null;
        }
    }
//leetcode submit region end(Prohibit modification and deletion)

}